The Essendon Football Club has launched a Federal Court challenge to anti-doping proceedings against its players.

Thirty-four past and present Bombers players have been issued with show cause notices by the Australian Sports Anti-Doping Authority (ASADA) on charges of using a prohibited substance, 16 months after an investigation was launched.

"The board concluded unanimously that the club is left with no alternative but to fight to protect the reputations and the livelihoods of our players," he said.

"There is no power or capacity under the ASADA Act to conduct a joint investigation. There never was.

"If we are right, and we believe we are, the court will declare the investigation null and void. We will seek a permanent injunction on the use of all information collected in that investigation.

"Enough is enough. We will not be bullied and will not allow our players to be hung out to dry any longer."

What is a show cause notice?

The Australian Sports Anti-Doping Authority (ASADA) has issued show cause notices to 34 Essendon players

In the show cause phase, players will be given 10 days to prove to ASADA they did not commit a doping infringement

During the 10-day period players may decide to launch a legal challenge against the notices

If ASADA's charges face a tribunal, the body will need to argue banned substances were administered

Any player found guilty faces a mandatory minimum two-year ban

If players demonstrate they were unwittingly given a prohibited substance, they may get a 50 per cent reduction on their penalty

Mr Little has also criticised the content of the show cause notices issued to players and the associated publicity.

"We are led to believe, through media reports, that the show cause letters, outlining the allegation against each player, do not contain any evidence or particulars to support the very serious allegations against each player," he said.

"After 16 months, our players are in no better position.

"How can our players possibly respond to a serious allegation - which was leaked through the media and then reinforced through an ASADA media blitz and grandstanding [on Friday] - without understanding the evidence against them?

"The process undertaken by ASADA has been severely compromised from the outset - to the extent that it is impossible for natural justice to be served."

He said the club was supporting the players with the legal challenges so they can remain focused on their football.

The players issued with show cause notices have 10 days to respond.

If found guilty, the players face sporting sanctions, not criminal, which have, as a starting point, a two-year suspension.

Suspended Essendon coach James Hird has launched a separate action against ASADA in the Federal Court.

Hird was suspended for 12 months last year over his involvement in the supplements scandal.

Stay loyal, Thompson tells fans

"Keep with us, stay loyal, turn up to the games especially this week against Melbourne and just keep supporting us. We love what you've done for us but now is a really critical time. Join the fight," he said.

ASADA's chief Ben McDevitt said earlier the players would not disadvantage themselves by assisting ASADA.

Keep with us, stay loyal, turn up to the games especially this week against Melbourne and just keep supporting us, we love what you've done for us but now is a really critical time.

Mark Thompson

"Players are at a critical point here, and players need to make some difficult decisions," he said.

"If there is substantial assistance given to the anti-doping organisation, as much as 75 per cent of that two years could be taken off."

Mr McDevitt has also intimated he is considering reaching a settlement.

"I would now like to actually enter into engagement with players and with legal counsel to discuss further how this might go because ... as much as anybody else, I want to see resolution and quick resolution of these matters," he said.

The club was banned from the 2013 AFL finals over its controversial supplements program.

The AFL also slapped the club with a $2 million fine, suspended Hird for a year, and stripped the Bombers of picks in the 2013 and 2014 drafts.

An AFL spokesman said: "AFL respects the right of all individual players and Essendon Football Club to explore their legal options. The AFL can make no comment at this time."

Legal process 'bloated', former anti-doping chief says

World Anti-Doping Agency (WADA) president John Fahey said he doubts the club will have success in the Federal Court, but if it does, it will be the first.

"In Europe, [not regularly], but [on] occasions, there have been a number of cases that have been taken by athletes from various sports," he said.

"Almost universally, I cannot recall a case in any of these challenges that have succeeded in not allowing the code to take effect."

Former head of the anti-doping authority, Richard Ings, said earlier the current system was "too complicated" and needed an overhaul.

"It is bloated, it is complicated, it is impenetrable for players and media and the public to understand," he said.

"It is too long, it's too expensive, it's too complicated, and it needs immediate reform and immediate streamlining to make it quicker, simpler, easier, lower cost, and most importantly, fairer.

"We're 16 months into an investigation. The show cause notices that have been issued today actually triggered the slow part of this process. If fully appealed, this could go on for literally years."

Essendon stalwart and father of Bombers captain Jobe Watson, Tim Watson, said if the ASADA charges are proven, the club has decieved the players.

"The players, they signed documentation that suggested that they would only be given supplements that were WADA and ASADA approved and if that's not the case, and if ASADA has evidence to the contrary of that, then they've been wilfully deceived," he said.

Nathan Jones, the captain of the Melbourne Demons, who the Bombers play on Sunday, said he sympathised with Essendon players.

"You feel for the position they're in," he said.

"I don't think any player envies them and there's a lot of compassion amongst the entire playing group across the AFL for the Essendon players.

ASADA said it has not decided how to proceed with anti-doping matters relating to players in the NRL.